#include <iostream>
#include <unordered_map>
#include <vector>

using namespace std;


void test()
{
    unordered_map<int,vector<int>> mp;
    mp[1].push_back(2);
    mp[2] = {3,4,5};
    mp[3].push_back(1);
    mp[4].push_back(2);
    mp[5].push_back(3);

    for(auto& [a,v] : mp)
    {
        cout << a << ": ";
        for(auto b : v) cout << b << " ";
        cout << endl;
    }
}

int main()
{
    test();
    

    return 0;
}